Field of Technology
The present disclosure relates to a thin-film transistor array substrate and a display device including the same.
Discussion of the Related Art
Recently, the importance of flat panel display (FPD) devices is increasing with the development of multimedia. Accordingly, various displays such as liquid crystal display (LCD) devices, plasma display panels (PDPs), field emission display (FED) devices, organic light emitting display (OLED) devices are put into practical use.
Methods for driving display devices include a passive matrix method and an active matrix method using a thin-film transistor. In the passive matrix method, an anode and a cathode are formed to be orthogonal to each other and a line is selected to be driven while, in the active matrix method, a thin-film transistor is connected to each pixel electrode to perform the driving according to on/off switching.
Thin-film transistors are very important not only for the basic characteristics of thin-film transistors such as electron mobility and leakage current, but also for durability and electrical reliability that can maintain a long lifetime. In particular, an active layer of the thin-film transistor may be formed mainly of amorphous silicon, polycrystalline silicon, or oxide semiconductor. Amorphous silicon is advantageous in that the film-forming process is simple and the production cost is low, but it is disadvantageous in that the electron mobility is as low as 0.5 cm2V/s. Oxide semiconductor has an on/off ratio of about 108 and a low leakage current, but it is disadvantageous in that it has an electron mobility of 10 cm2V/s, which is lower than that of polycrystalline silicon. Polycrystalline silicon has high electron mobility of about 100 cm2V/s, but it is disadvantageous in that it has a low on/off ratio compared to oxide semiconductor and it is expensive to apply it to a large area. Accordingly, studies for improving characteristics of the thin-film transistors such as electron mobility, leakage current, on/off ratio, etc., are being conducted.